1. Field
Some example embodiments relate to graphene, and more particularly, to graphene as a material for electronic devices.
2. Description of the Related Art
Graphene is a two-dimensional structure of a monatomic layer of carbon. Graphene has a unique band structure, a relatively high electron mobility of about 200,000 cm2V−'s−1, and a quantum hole effect (QHE) at room temperature. However, graphene has no band gap, and is not applicable in electronic devices, specifically in switching devices, such as transistors. Therefore, research has been conducted to render a band gap to graphene.
For example, to open a band gap in graphene, graphene may be patterned into nanoribbons having a width of about 10 nm or less. However, forming graphene nanoribbons with a band gap requires the use of expensive special equipment. Furthermore, manufacturing a relatively large array of graphene nanoribbons for integrated circuits is extremely difficult with the current technology.
Another method of opening a band gap in graphene is using AB-stacked graphene. A band gap in graphene may be induced by breaking the symmetry in a band structure of a two-layered graphene laminate with an AB-stacked structure. For example, a relatively strong electric field may be applied between opposite surfaces of the two-layered graphene laminate to open a band gap in the AB-stacked graphene. This method uses a relatively high voltage.
Another method of opening a band gap in graphene is doping one or opposite surfaces of single-layer graphene or double-layer graphene with a dopant. However, a charge transfer from the dopant to the graphene may cause a doping state in graphene, consequently leading to increased scattering and reduced mobility of charges in graphene. Furthermore, it is difficult to control a doping concentration of the dopant in graphene with this method.